The Influences of Holmium on Microstructure and Properties of <i>In Situ</i> Mg₂Si/Al Composites

Abstract

In this study, Mg2Si in in-situ Mg2Si/Al composites were subjected to modification treatment using rare earth element Holmium (Ho). The phase composition and microstructure before and after modification of Mg2Si were also analyzed using X-ray diffraction (XRD) and optical microscope (OM); in addition, its mechanical properties were detected as well. The results showed that moderate addition of rare earth element Ho in in-situ Mg2Si/Al composites presents good modification effects on Mg2Si, the morphology of primary Mg2Si was changed from cross shape before modification to dispersed irregular mass; optimal modification effect was obtained when 0.4% rare earth element Ho was added. Under this condition, the average size of primary Mg2Si was decreased from 74 μm before modification to 16 μm; its mechanical properties were promoted significantly; and its tensile strength increased from 134 MPa before modification to 174.6 MPa, its brinell hardness elevated from 76 HB to 90 HB.